October 24, 2012 – A 6.5 Magnitude Earthquake Struck Western Costa Rica: A powerful earthquake struck Costa Rica’s Pacific coast on Tuesday, swaying buildings and sending people running into the streets in the nation’s capital of San Jose. It was 6:45PM Oct. 23rd at the epicenter, however, it was 12:45AM at GMT (London).
The 6.5-magnitude quake was centered in the Guanacaste region of the Central American country, only 5 miles (8 kilometers) from the popular tourist town of Nicoya, according to the U.S. Geological Survey. It had a depth of 24.5 miles (39.5 kilometers), according to a preliminary report. Further, the quake hit 38 miles SSE of Liberia, Costa Rica; 79 miles SSW of San Carlos, Nicaragua; and 88 miles west of San Jose, Costa Rica (see maps).
At the beach of Matapalo, an hour drive from Nicoya, residents said they heard a roaring sound when the quake struck.
‘‘I’m shaken. But it doesn’t feel close to how it sounds like. The sound was deafening,’’ said Alberto Canales, a receptionist at the Hotel Riu Guanacaste.
Extensive diversity and complexity of tectonic regimes characterizes the perimeter of the Caribbean plate, involving no fewer than four major plates (North America, South America, Nazca, and Cocos). Inclined zones of deep earthquakes (Wadati-Benioff zones), ocean trenches, and arcs of volcanoes clearly indicate subduction of oceanic lithosphere along the Central American and Atlantic Ocean margins of the Caribbean plate, while crustal seismicity in Guatemala, northern Venezuela, and the Cayman Ridge and Cayman Trench indicate transform fault and pull-apart basin tectonics.
The region suffered an even more powerful earthquake last month, when a 7.6 earthquake rattled the same coasts, causing panic, evacuations but minor damage.
Seismologists both in the U.S. and Costa Rica said the quake is probably an aftershock of the Sept. 5 major earthquake.
‘‘It is a very good likelihood that we are looking at an aftershock,’’ said USGS geophysicist Rafael Abreu. (Credits – USGS)
The Master of Disaster